Nenya 0.4.0

Changelog

• 2279420 Add code review follow-ups: Bouncer test and comment fix
• a374c75 Fix interceptor CanHandle logic when MaxContext is unknown
• aff61ab feat: 002 implement local engine lifecycle
• 6380e42 feat: add bidirectional Anthropic Messages API support
• 8f0dc77 feat: add context-limit aware retry with summarization fallback
• e343fb9 feat: add metrics and logging instrumentation for post-v0.3.0 features
• 2772779 feat: enrich Ollama model discovery with /api/show metadata
• c6b4c17 feat: implement pluggable interceptor chain for content preprocessing
• 81df23e feat: implement structured error handling with error_kind field
• 1b1fdae feat: strip unsupported tool_choice field from Ollama requests
• 21f0016 fix: merge built-in provider defaults into partial user configs